This invention relates to steering systems, specifically steering systems for use in oil, gas, geothermal, and/or horizontal drilling. The ability to accurately adjust the direction of drilling in downhole applications is desirable to direct the borehole toward specific targets. A number of steering systems have been devised for this purpose.
One such system is disclosed in U.S. Pat. No. 2,498,192 to Wright, which is herein incorporated by reference for all that it contains. Wright discloses an apparatus for drilling well bores at a desired angle and in a predetermined direction, whereby the apparatus is particularly useful in directional drilling, side-tracking and similar operations.
U.S. Pat. No. 6,749,031 to Klemm, which is herein incorporated by reference for all that it contains, discloses a drilling system having a drilling head fixed to a drill string which comprises an outer pipe and a percussion string inserted therein, wherein the percussion string comprises a plurality of rods which bear against each other with their end faces. One object of the present invention is to provide a drilling system with an inner percussion string, which permits a greater variation in the drilling direction and which can be used as a directional drilling system. To attain that object the outer pipe is adapted to be deformable along its longitudinal axis and the end faces which bear against each other of two rods are so designed that they bear against each other substantially in surface contact upon inclined positioning of the axes of the two rods relative to each other.
U.S. Pat. No. 7,013,994 to Eddison, which is herein incorporated by reference for all that it contains, discloses a directional drilling apparatus for use in drilling a deviated bore comprising a mandrel for mounting to a drill string and having a main axis. A nonrotating mass is rotatably mounted on the mandrel and has a center-of-gravity spaced from the mandrel axis. The apparatus further comprises an offsetting arrangement including a nonrotating offsetting portion rotatably mounted on the mandrel, coupled to the mass, and having an outer profile defining an offset relative to the mandrel axis, and a bearing portion rotatably mounted on the offsetting portion. In use, the apparatus is run into an inclined bore on a string, and the offsetting portion is oriented relative to the mass. When the string is rotated the mass tends towards an orientation with its center-of-gravity positioned towards the low side of the bore and thus tends to maintain the offsetting portion in a desired relative orientation in the bore, the bearing portion rotationally isolating the offsetting portion from the bore wall.